In the current market of products for infusion, such as coffee, barley coffee, tea and camomile, the use of single-dose “pods” has increased considerably and a very popular way of making American-style coffee is now to use such pods in specially designed machines, even for household or office use (that is, for small to medium quantities).
This specification does not concern other forms of filter bags normally used to make American-style coffee and consisting of a “maxi dose” bag designed to be placed in a funnel-like container at the top of a machine that supplies boiling hot water. The hot water comes into contact with the coffee filter bag producing a brew of coffee which is simply allowed to drip into a cup below.
Unlike this type of solution—which is widely used and extremely popular—pods used to brew a single serving of beverage usually consist of two portions of filter paper placed one over the other and sealed to enclose a single product dose of circular shape.
In the specific case of pods for American-style coffee, the product is not (and must not be) excessively compressed, which means that it remains relatively loose inside the pod.
For technical reasons linked to the type of machines used to make them, the pods have an asymmetrical profile, that is to say, with one flat surface (defined by one of the portions of filter paper) and one cupped surface (defined by the other portion of filter paper) containing the dose of infusion product.
One prior art method and related apparatus for making this type of pod is described in patent EP-432.126. The method disclosed therein comprises the following sequence of steps:                feeding a first web of filter paper to a station where suitable means cause the filter paper to be wrinkled or crinkled;        moving the web of filter paper along the surface of a forming drum, provided with circular pockets and with suction means, and simultaneously training a belt in contact with the filter paper, with the filter paper being between the belt and the surface of the forming drum, so that spaced areas of the belt are pulled by suction into the pockets in the drum, drawing the filter paper along with it in such a way as to form a succession of pouches in the filter paper;        filling a dose of product into each pouch by means of a dosing station located downstream of the suction drawing belt in the direction of rotation of the pouch forming drum and consisting of a second revolving drum synchronised with the pouch forming drum;        joining the first web of filter paper, provided with the product filled pouches, to a second web fed at a respective sealing station located downstream of the filling station, again relative to the direction of rotation of the forming drum;        cutting out the pods thus made and feeding them out towards further packaging stations.        
This method and the apparatus that embodies it have several disadvantages due to:                the need to pre-process the web of filter paper to make it suitable for forming the pouches, which means that the apparatus requires an additional station; this operation being necessary especially when two or more parallel rows of pouches are formed in the filter paper web; and        the possible difficulty of accurately controlling the volume of product filled into each pouch on account of the two revolving cylindrical surfaces of the drums (dosing and forming); this can cause a certain amount of product being lost as it is gravity fed into the pouch.        
The aim of the present invention is to overcome the above mentioned drawbacks by providing a method and an apparatus for making pods containing products for infusion that is at once practical, fast, reliable in dosing the product and structured in such a way as to require a limited number of operating stations.